With the advent of the new 10GBASE-CX4 Ethernet media-type technology, methods of extending the range of 10-Gigabit networks beyond the 15-meter range accommodated by CX4 have been explored. One such method is to attach an optical-media converter (OMC) to a CX4 ports. OMCs allow 10-Gigabit interconnections of up to 300 meters over the copper-wire connectivity associated with CX4.
In order to power the OMC, a method of providing current through a network device interface (e.g., a network interface card) has been devised. This method employs shield connections through the interface as signal pins to convey low-frequency DC levels to power the OMC. Such signal pins may further be used for the exchange of regulating and other signals between the interface and the OMC.
FIG. 1 is an exemplary schematic illustration of such a method. A pair of dashed lines defines an interface 10 between circuitry residing on an OMC 20, and circuitry residing on a connector, such as a network interface card 30, residing in an electronic device, such as a computer system (not shown). The interface 10 comprises connection pins 40 that serve as connection points for the exchange of corresponding signals VCC_OUT, TYPE and ODIS (described in more detail below) between the OMC 20 and the interface card 30. The interface card 30 includes a hot-swap control circuit 50 and a laser-disable circuit 60. A current supply circuit 70 residing in the electronic device supplies current to the hot-swap control circuit 50 at connection pins VCC and V_FET_BIAS.
In operation, the hot-swap control 50 allows power to be supplied to a device via VCC_OUT only if the device qualifies itself according to parameters established by a window comparator 75 in combination with a pull-up resistor 76. The window comparator 75 enables the device to be powered via VCC_OUT upon mating with the interface card 30 only if the voltage of the TYPE signal associated with the device is within a validation range of voltages (e.g., between ⅓ and ⅔ of the supply voltage VCC). If, for example, a copper cable (i.e., a grounded attachment) was attached to the TYPE pin of the interface card 30, the voltage of the TYPE signal would be 0 and no power would be supplied via VCC_OUT. Similarly, if there is nothing attached to the TYPE pin of the interface card 30, the pull-up resistor 76 pulls the TYPE voltage up to VCC and no power would be supplied via VCC_OUT. In the example illustrated in FIG. 1, the TYPE signal associated with the OMC 20 is tied to ground by a resistor 77. If the resistor 77 and the resistor 76 associated with the hot-swap control 50 have an equal resistance value, a voltage divider is created at the TYPE signal. Consequently, the TYPE signal is approximately ½ of the supply voltage VCC (i.e., within the validation range) and power would be supplied to the OMC via VCC_OUT.
The laser-disable circuit 60 allows the computer system to enable or disable, via the ODIS signal, a laser 80 associated with the OMC 20.
For purposes of compatibility and product support, computer system manufacturers may desire that their systems automatically discriminate certain OMCs from others (i.e., OMCs that are not produced by approved sources). Such discrimination may ideally be implemented by withholding VCC_OUT from OMCs that the manufacturer does not approve of.